In 1725 Jean-François Mercier first visited Illinois, where he had relatives in the various villages. At Fort de Chartres (near Prairie du Rocher, Ill.) he purchased the Canadian inheritance of one of them, and, as a young man of property, returned to his father’s Quebec home. On 17 Feb. 1726 he married Catherine Lafontaine at Sainte-Foy. Soon after, his elderly father turned over his home and blacksmith shop to him and to a son-in-law, and for a few years Jean-François apparently practised the trade of blacksmith in Quebec.

The memory of the fertile lands of the Illinois remained with him, however, and some time between 1732 and 1735 he went to Cahokia to stay. He was one of the first to bring a wife to the mission settlement. His brother Jean-Paul had been serving there since 1718, when he and another priest accompanied their superior, Goulven Calvarin*, to the Sainte-Famine mission to the Tamaroas. By 1735 Jean-Paul was in charge, and his plan of the mission seigneury, made in that year, shows the house and barn of Jean-François on the mission property. By 1752, except for the mission itself, his was the largest single property in Cahokia. That he was the only head of a household called “Sieur” in the 1752 census indicates the social status he had achieved. He resided on three acres with his wife and three children, and with two hired workers and four slaves cultivated about 70 acres of land. Documents which refer to him as a voyageur-négociant reveal that he was also active in trade.

Jean-Paul Mercier died in 1753; his successor, Jacques-François Forget Duverger, fled when the region was ceded to Britain in 1763, and the mission was left without its own priest. Sébastien-Louis Meurin* of Prairie du Rocher, who visited Cahokia at intervals to officiate, wrote in 1769: “I usually have living with me there the brother of Monsieur Mercier, the very worthy deceased missionary. . . . It is he who cares for the church in my absence.” Jean-François Mercier, bereft of immediate family, apparently spent his last days serving his late brother’s church. By June 1770 he was dead. His will, naming his sister-in-law Marianne Dornon, née Lafontaine (the widow of Antoine Giard), as his heir, was contested by Joseph-Marie Mercier, his half-brother, who had moved to Illinois about 1743.

We acknowledge the support of the Government of Canada through the Department of Canadian Heritage. Nous reconnaissons l’appui du gouvernement du Canada par l’entremise du ministère du Patrimoine canadien.